2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
229 lines
5.8 KiB
Groff
229 lines
5.8 KiB
Groff
.\" $NetBSD: setjmp.3,v 1.17 2008/05/31 16:15:07 enami Exp $
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.\"
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.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the American National Standards Committee X3, on Information
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.\" Processing Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)setjmp.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 1, 2008
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.Dt SETJMP 3
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.Os
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.Sh NAME
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.Nm sigsetjmp ,
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.Nm siglongjmp ,
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.Nm setjmp ,
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.Nm longjmp ,
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.Nm _setjmp ,
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.Nm _longjmp ,
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.Nm longjmperror
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.Nd non-local jumps
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In setjmp.h
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.Ft int
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.Fn sigsetjmp "sigjmp_buf env" "int savemask"
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.Ft void
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.Fn siglongjmp "sigjmp_buf env" "int val"
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.Ft int
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.Fn setjmp "jmp_buf env"
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.Ft void
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.Fn longjmp "jmp_buf env" "int val"
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.Ft int
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.Fn _setjmp "jmp_buf env"
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.Ft void
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.Fn _longjmp "jmp_buf env" "int val"
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.Ft void
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.Fn longjmperror void
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.Sh DESCRIPTION
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The
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.Fn sigsetjmp ,
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.Fn setjmp ,
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and
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.Fn _setjmp
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functions save their calling environment in
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.Fa env .
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Each of these functions returns 0.
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.Pp
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The corresponding
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.Fn longjmp
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functions restore the environment saved by the most recent
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invocation of the respective
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.Fn setjmp
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function.
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They then return so that program execution continues as if the corresponding
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invocation of the
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.Fn setjmp
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call had just returned the value specified by
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.Fa val ,
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instead of 0.
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.Pp
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Pairs of calls may be intermixed, i.e., both
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.Fn sigsetjmp
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and
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.Fn siglongjmp
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as well as
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.Fn setjmp
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and
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.Fn longjmp
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combinations may be used in the same program.
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However, individual calls may not, e.g., the
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.Fa env
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argument to
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.Fn setjmp
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may not be passed to
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.Fn siglongjmp .
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.Pp
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The
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.Fn longjmp
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routines may not be called after the routine which called the
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.Fn setjmp
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routines returns.
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.Pp
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All accessible objects have values as of the time
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.Fn longjmp
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routine was called, except that the values of objects of automatic storage
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invocation duration that do not have the
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.Li volatile
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type and have been changed between the
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.Fn setjmp
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invocation and
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.Fn longjmp
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call are indeterminate.
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.Pp
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The
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.Fn setjmp Ns / Ns Fn longjmp
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function pairs save and restore the signal mask while
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.Fn _setjmp Ns / Ns Fn _longjmp
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function pairs save and restore only the register set and the stack.
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(See
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.Fn sigprocmask 2 . )
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.Pp
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The
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.Fn sigsetjmp Ns / Ns Fn siglongjmp
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function pairs save and restore the signal mask if the argument
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.Fa savemask
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is non-zero.
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Otherwise, only the register set and the stack are saved.
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.Pp
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In other words,
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.Fn setjmp Ns / Ns Fn longjmp
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are functionally equivalent to
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.Fn sigsetjmp Ns / Ns Fn siglongjmp
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when
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.Fn sigsetjmp
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is called with a non-zero
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.Fa savemask
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argument.
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Conversely,
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.Fn _setjmp Ns / Ns Fn _longjmp
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are functionally equivalent to
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.Fn sigsetjmp Ns / Ns Fn siglongjmp
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when
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.Fn sigsetjmp
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is called with a zero-value
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.Fa savemask .
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.Pp
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The
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.Fn sigsetjmp Ns / Ns Fn siglongjmp
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interfaces are preferred for maximum portability.
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.Sh ERRORS
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If the contents of the
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.Fa env
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are corrupted or correspond to an environment that has already returned,
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the
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.Fn longjmp
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routine calls the routine
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.Xr longjmperror 3 .
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If
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.Fn longjmperror
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returns, the program is aborted (see
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.Xr abort 3 ) .
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The default version of
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.Fn longjmperror
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prints the message
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.Dq Li longjmp botch
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to standard error and returns.
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User programs wishing to exit more gracefully should write their own
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versions of
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.Fn longjmperror .
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.Sh SEE ALSO
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.Xr sigaction 2 ,
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.Xr sigaltstack 2 ,
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.Xr sigprocmask 2 ,
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.Xr pthread_sigmask 3 ,
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.Xr signal 3
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.Sh STANDARDS
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The
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.Fn setjmp
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and
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.Fn longjmp
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functions conform to
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.St -ansiC .
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The
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.Fn sigsetjmp
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and
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.Fn siglongjmp
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functions conform to
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.St -p1003.1-90 .
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.Sh CAVEATS
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Historically, on
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.At V ,
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the
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.Fn setjmp Ns / Ns Fn longjmp
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functions have been equivalent to the
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.Bx
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.Fn _setjmp Ns / Ns Fn _longjmp
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functions and do not restore the signal mask.
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Because of this discrepancy, the
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.Fn sigsetjmp Ns / Ns Fn siglongjmp
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interfaces should be used if portability is desired.
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.Pp
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Use of
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.Fn longjmp
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or
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.Fn siglongjmp
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from inside a signal handler is not as easy as it might seem.
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Generally speaking, all possible code paths between the
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.Fn setjmp
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and
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.Fn longjmp
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must be signal race safe.
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Furthermore, the code paths must not do resource management
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(such as
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.Xr open 2
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or
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.Xr close 2 )
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without blocking the signal in question, or resources might
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be mismanaged.
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Obviously this makes
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.Fn longjmp
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much less useful than previously thought.
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